Method of regulating plant growth

ABSTRACT

SEMICARBAZIDES, ESPECIALLY THE TETRAALKYLATED THIOSEMICARBAZIDES AND BIURET DERIVATIVES, ESPECIALLY THE MONOAND DITHIOBIURET DERIVATIVES HAVE DEMONSTRATED EFFECTIVE GROWTH REGULATING ACTIVITY. EXEMPLARY OR PREFERRED SEMICARBAZIDES ARE THOSE HAVING THE FORMULA:   R1-N(-R2)-C(=Y)-N(-X)-N(-R4)-R3   WHERE R1 AND R4 EACH REPRESENT AND UNSUBSTITUTED OR SUBSTITUTED C1-C30 HYDROCARBYL GROUP, PREFEFERABLY C1-C10, AND X CAN BE EITHER HYDROGEN, SAID UNSUBSTITUTED OR SUBSTITUTED HYDROCARBYL GROUP, AND Y CAN BE O OR S. EXEMPLARY OF PREFERRED BIURET DERIVATIVES ARE THOSE HAVING THE FORMULA: R5-N(-R6)-C(=Y)-N(-N(-R9)-R10)-C(=Y)-N(-R7)-R8 WHERE R5-R10 CAN BE H, UNSUBSTITUTED OR SUBSTITUTED C1C30 HYDROCARBYL GROUP, PREFERABLY C1-C10, AND Y CAN BE O ORS, AND COMBINATIONS THEREOF. TYPICAL R1-R10 HYDROCARBYL GROUPS INCLUDE: (1) SATURATED OR UNSATURATED, ACYCLIC OR CYCLIC, ALIPHATICS SUCH AS, E.G,M ETHYL, PROPARGYL, CYYCLOHEXY, CYCLOHEXENYL, ETC., AND (2) AROMATIC OR HETEROAROMATIC RADICALS, SUCH AS PHENYL, PYRIDYL, ETC.

carbyl groups include:

United States Patent 3,741,746 METHOD OF REGULATIN G PLANT GROWTHRichard J. Marrese, Wyckofi, Gordon C. Edwards, Cranford, and JamesZielinski, Kenilworth, N.J., assignors to Esso Research and EngineeringCompany No Drawing. Filed Nov. 12, 1969, Ser. No. 876,144 Int. Cl. A01n9/12 US. Cl. 71-72 4 Claims ABSTRACT OF THE DISCLOSURE Semicarbazides,especially the tetraalkylated thiosemi carbazides and biuretderivatives, especially the monoand dithiobiuret derivatives havedemonstrated effective growth regulating activity. Exemplary orpreferred semicarbazides are those having the formula:

where R, and R each represent an unsubstituted or substituted (l -Chydrocarbyl group, preferably C -C and X can be either hydrogen, saidunsubstituted or substituted hydrocarbyl group, and Y can be 0 or S.

Exemplary of preferred biuret derivatives are those having the formula:

where R R can be H, unsubstituted or substituted C C hydrocarbyl group,preferably C C and Y can be 0 or S, and combinations thereof. Typical R-R hydro- (l) saturated or unsaturated, acyclic or cyclic, aliphaticssuch as, e.g., ethyl, propargyl, cyclohexyl, cyclohexenyl, etc.; and (2)aromatic or heteroaromatic radicals, such as phenyl, pyridyl, etc.

This invention relates to the use of tetra-substitutedthiosemicarbazides, as well as monothiobiuret and dithiobiuretderivatives as growth regulants.

In one aspects, this invention relates to the use of the aforesaidcompounds as fruit thinning agents. In another aspect, this inventionrelates to the use of the aforesaid compounds as plant growth regulants.In yet another aspect, this invention relates to the use of theaforesaid compounds as crop harvest aids.

The broad class of growth regulants are those compounds having anability to regulate vegetative, flowering and fruiting characteristicsof crops produced throughout the world. With growth regulators, it isnow possible to chemically control and alter the physiological processesin the growing crop; which up until the advent of such technology couldonly be triggered by natural and climatic conditions. Thus, it ispossible to produce crops of higher quality and with greater flexibilityin harvesting procedures. Various theories have been proposed forexplaining the mechanisms of chemical growth regulants such as, theyprevent fertilization of freshly opened flowers by 6 inducing anincompatible condition between the stylar tissue and the pollen tubes.Another theory is that a crop is thinned because of an increased drop inyoung fruitlets due to accelerated ethylene generation by the particulartreatment. Developing fruitlets on weak spurs for food supply possessthe most resistance to the chemical treatment.

Whatever may be the actual mechanism involved in chemical fruit thinningor in the removal of unwanted growth for particular plants, or in theabscission of the fruit when the plant matures thereby regulating theharvest season, the growth regulants have indeed opened up an entirelynew field for agricultural chemicals.

An object of the present invention is to provide a process for thinningfruit plants, such as citrus, stone and pome fruits, small fruits andnuts, in which a chemical material may be employed over a relativelywide range of concentrations without danger of over-thinning, as well ascausing foliage and fruit damage. Another object of the invention is toprovide a process of thinning fruits with a chemical agent which caneffectively be applied to the trees over a relatively long period oftime beginning with full bloom.

Yet another object of the invention is to provide a process foradjusting the rate and timing of abscission of undesirable late flowersand fruitlets prior to mechanical harvesting of mature crops.

A still further object of the invention is to provide a process forcontrolling the rate of final development and maturation of crops so asto regulate the timed abscission of the mature fruit, vegetables, nutsor berries.

A still further object of the invention is to provide a process fordelaying the onset of normal maturation processes, such as, senescenceor defoliation, thereby providing continued vegetative growth, as Wellas more intensely colored foliage.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description.

Briefly, this invention relates to a method for regulating the growth ofplants, said method comprising the step of treating growing plants witha material of the group consisting of those compounds represented by oneof the following formulae:

where R -R can be unsubstituted or substituted C C hydrocarbyl,preferably C -C and X can be hydrogen, or unsubstituted or substituted CC hydrocarbyl, and Y can be 0 or S.

where R R can be H, or unsubstituted or substituted hydrocarbyl; and Ycan be 0 or S, and combinations thereof, in a concentration and amountsufficient to alter the growth characteristics of said plants.

with a limited food supply may be more susceptible than those with anabundant supply so that the elimination of clusters where two or morefruits have set on the same spur can be explained on the basis ofcompetition for food; that is, the fruitlets having the greatestadvantage The material which we have discovered to possess theabove-mentioned desirable properties is represented by one of thefollowing formulae:

where R R can be unsubstituted or substituted C -C hydrocarbyl,preferably C C and X can be hydrogen, or unsubstituted or substituted CC hydrocarbyl, preferably C -C and Y can be or S.

where R -R can be H, or unsubstiuted or substituted hydrocarbyl; and Ycan be 0 or S, and combinations thereof. Typical R -R hydrocarbyl groupsinclude: (1) saturated or unsaturated, acyclic or cyclic, aliphaticssuch as, e.g., ethyl, propargyl, cyclohexyl, cyclohexenyl, etc.; and (2)aromatic or heteroaromatic radicals such as phenyl, pyridyl, etc.

These compounds and their methods of preparation are described in acopending case hearing Ser. No. 821,975 which was filed on May 5, 1969,now abandoned, in the name of James Zielinski and entitled Semicarbazideand Biuret Derivatives and Their Use as Agricultural Pesticides andAnimal Health Agents.

The compounds may be applied to the plants any time throughout thegrowing season, depending on the type of effect desired, in a number ofways. When used, the semicarbazides, biurets and monoor dithiobiurets,are preferably formulated with a suitable inert carrier or diluentthereof.

The term carrier or diluent as used herein means a material, which canbe inorganic or organic and synthetic or of natural origin, with whichthe active semicarbazides and monoor dithiobiurets are mixed orformulated to facilitate its storage, transport, and handling andapplication of the plants or fungi to be treated. The carrier ispreferably biologically and chemically inert and, as used, can be asolid or fluid. When solid carriers are used, they are preferablyparticulate; however, other shapes and sizes of solid carrier can beemployed as well. Such preferable solid carriers can be naturaloccurring minerals, although subseqeuntly subjected to grinding,sieving, purification, and/ or other treatments, including for example,gypsum; tripolite diatomaceous earth; mineral silicates such as mica,vermiculite, talc, and pyrophyllite, clays of the montmorillonite,kaolinite, or attapulgite groups; calcium or magnesium limes, or calciteand dolomite; etc. Carriers produced synthetically, as for example,synthetic hydrated silica oxides and synthetic calcium silicates canalso be used, and many proprietary products of this type are availablecommercially. The carrier can also be an elemental substance such assulfur or carbon, preferably an activated carbon.

Fluid carriers can be liquids, as for example, water, or an organicfluid, including a liquefied normally vaporous or gaseous material, or avaporous or gaseous material, and can be solvents or nonsolvents for theactive material. For example, the horticultural petroleum spray oilsboiling in the range of from about 275 to about 575 F., or boiling inthe range of about 575 F. to about 1,000 F. and having an unsulfonatableresidue of at least about 75% and preferably of at least about 90%, ormixtures of these two types of oil, are particularly suitable liquidcarriers.

The carrier can be mixed or formulated with the active material duringits manufacture or at any stage subsequently. The carrier can be mixedor formulated with the active material in any proportion depending onthe nature of the carrier. One or more carriers, moreover, can be usedin combination.

The compositions of this invention can be concentrates, suitable forstorage or transport and containing, for example, from about 5 to about90% by weight of the active thiosemicarbazide and monoor dithiobiuretingredient, preferably from about 20 to about wt. percent. Theseconcentrates can be diluted with the same or different carrier to aconcentration suitable for application. The compositions of thisinvention may also be dilute compositions suitable for application. Ingeneral, concentrations of about 0.1 to about 10% by weight, of activematerial based on the total weight of the composition are satisfactory,although lower and higher concentrations can be applied if necessary.

The compositions of this invention can also be formulated as dusts.These comprise an intimate admixture of the active thiosemicarbazide andmonoor dithiobiuret ingredients and a finely powdered solid carrier suchas aforedescribed. The powdered carriers can be oiltreated to improveadhesion to the surface to which they are applied. These dusts can beconcentrates, in which case a highly sorptive carrier is preferablyused. These require dilution with the same or a different finelypowdered carrier, which can be of lower sorptive capacity, to aconcentration suitable for application.

The compositions of the invention can be formulated as wettable powderscomprising a major proportion of the thiosemicarbazides, biurets, andmonoor dithiobiurets mixed with a dispersing, i.e., defiocculating orsuspending agent, and, if desired, a finely divided solid carrier and/ora wetting agent. The thiosemicarbazides, biurets, and monoordithiobiurets can be in particulate form or adsorbed on the carrier andpreferably constitute at least about 10%, more preferably at least about25%, by weight of the composition. The concentration of the dispersingagent should in general be between about 0.5 and about 5% by weight ofthe total composition, although larger or smaller amounts can be used ifdesired.

The dispersing agent used in the composition of this invention can beany substance having definite dispersing, i.e., deflocculating orsuspending properties, as distinct from wetting properties, althoughthese substances can also possess wetting properties as well.

The dispersant or dispersing agent used can be protective colloids suchas gelatin, glue, casein, gums, or a synthetic polymeric material suchas polyvinyl alcohol and methyl cellulose. Preferably, however, thedispersants or dispersing agents used are sodium or calcium salts ofhigh molecular weight sulfonic acids, as for example, the sodium orcalcium salts of lignin sulfonic acids derived from sulfite cellulosewaste liquors. The calcium or sodium salts of condensed sulfonic acid,for example, the products known as Tamol 731 are also suitable.

The wetting agents used can be nonionic type surfactants, as forexample, the condensation products of fatty acids containig at least 12,preferably 16 to 20, carbon atoms in the molecule, or abietic acid ornaphthenic acid obtained in the refining of petroleum lubricating oilfractions with alkylene oxides such as ethylene oxide or propyleneoxide, or with both ethylene oxide and propylene oxide, as for example,the condensation product of oleic acid and ethylene oxide containingabout 6 to 15 ethylene oxide units in the molecule. Other nonionicwetting agents like polyalkylene oxide polymers, commercially known asPluronics can be used. Partial esters of the above acids with polyhydricalcohols such as glycerol, polyglycerol, sorbitol, or mannitol can alsobe used.

Suitable anionic wetting agents include the alkali metal salts,preferably sodium salts, of sulfuric acid esters or sulfonic acidscontaining at least carbon atoms in a molecule, for example, the sodiumsecondary alkyl sulfates, dialkyl sodium sulfosuccinate available underthe registered trademark Teepol, sodium salts of sulfonated castor oil,sodium dodecyl benzene sulfonate.

The final wettable powder should preferably have an average particlesize of 5-10/L.

Where the toxicant itself is a liquid, there materials can be sprayed oncrops or fungi without further dilution.

Petroleum hydrocarbon fractions used as solvents should preferably havea flash point above 73 F., an example of this being a refined aromaticextract of kerosene. Auxiliary solvents such as alcohols, ketones, andpolyalkylene glycol ethers and esters can be used in conjunction withthese petroleum solvents.

The treatment rates range from .1 to 3 lbs./acre of the activeingredient with a preferred range of .1 to /3 lbs./ acre. The materialsare applied at optimum timing so as to have the desired effect on theparticular crop. Therefore, applications may be made once or more thanonce depending on plant species or varieties, cultural conditions,environmental conditions for the particular type of effect desired.

The present invention is further illustrated in greater detail by thefollowing examples.

EXAMPLE 1 Percent l,1,5,5-tetramethyl-3-dimethylaminodithiobiuret 50Kaolin clay 19 Calcium stearate 20 Polymerized organic salt of analkylaryl sulfonic acid r "a 5 Alkylaryl polyoxy ethylene glycol 4Glycerol phthalate resin 2 The following results were observed eightweeks after the initial application: The potato plants treated at onehalf pound per acre with said compound exhibited the following growthregulant effects as compared to untreated controls: intense greencoloration, greatly increased vegetative growth and significantlyreduced leaf size.

At the termination of the tests, the potatoes treated at one half poundper acre with said compound, remained in a vegetative state while thecontrolled plants exhibited the normal senescence state of terminalgrowth at the end of the season. The treated plants produced almost notubers and those tubers that were produced were uniformly small in size.

EXAMPLE 2 Apple seedling were treated with said compound at 600 partsper million active ingredient concentrations in the same formulation inwater as Example 1, directly onto the foliage to run off and placed inthe greenhouse for subsequent observation. It was noted that the growthof the treated seedlings was retarded compared to controls therebygiving a stunted appearance to the so-treated apple seedlings.

EXAMPLE 3 Young peach, apple and cherry trees were treated with1,1,5,5-tetramethyl 3 dimethylaminodithiobiuret at 300 to 600 parts permillion active ingredient concentration, in the same formulation inwater as Example 1, directly onto the foliage to run off, and placed inthe greenhouse for subsequent observation. Within one week the treesexhibited various plant hormonal effects, malformed leaves,

uneven surface and manifested differences in intensity and shade of thegreen color.

EXAMPLE 4 McIntoch, Cortland, Golden Delicious and Red Delicious appletrees were treated with l,l,5,5-tetramethyl-3- dimethylaminodithiobiuretat one half pound per acre active ingredient concentration in theformulation as given in Example 1, per hundred gallons of water,directly onto the foliage, on a weekly application schedule for eightweeks.

It was noted that the 1,l,5,5-tetramethyl-3-dimethylaminodithiobiurettreatments had caused reduced fruit set on the apple trees with onlyfourfive apples developing on each tree, whereas the check trees had thenormal load of fruit.

EXAMPLE 5 EXAMPLE 6 Tomato plants were treated with1,1,5,5-tetramethyl-3- dimethylaminodithiobiuret at one quarter poundper acre active ingredient concentration in the formulation given inExample 1, per gallons of water. The same treatment was continued on aweekly basis for ten applications.

:It was noted that the treated tomato plants had fewer number of fruitsand smaller fruit than checked plants. The leaves on the treated plantswere curled in some instances and the treated plants were greener andmore vegetative in appearance.

EXAMPLE 7 0.2 grams of a one percent suspension of1,1,5,5-tetramethyl-3-dimethylaminodithiobiuret and 1,1,4,4tetramethylthiosemicarbazide in lanolin were placed around the lowerstem of each of two replicate five-week old Deltapine cotton plants.

The abscission of the previously debladed lowest petiole on each plantwas determined seven days following treatment, by application of a 5 gm.pressure to the outer portion of the petiole. The treated plantsexhibited accelerated petiole abscission as shown by the following datafor each replicate:

Treatment: Observed effect Lanolin only control None, none.1,1,5,5-tetramethyl-3-dimethyl- Abscissed, none.

aminodithiobiuret. 1,1,4,4-tetramethylthiosemi- Abscissed, abscissed.

carbazide.

EXAMPLE 8 1,1,5,5-tetramethy1 3 dimethylaminodithiobiuret formulated asin Example 1, and suspended in water, was applied directly to thefoliage of trees of two peach varieties under the conditions shown inthe table below, to four replicate trees each, to run-ofl.

1,1,5,5 tetramethyl-3-dimethylaminodithiobiuret provided desirable peachthinning activity as indicated in the table below:

In field studies, 1,1,5,5-tertamethyl-3-dimehtylaminodithiobiuretformulated as in Example 1, was applied directly to the foliage of sixreplicate trees of Redhaven variety at 8.5 mm. average ovule length, torun-01f.

The treated and controlled trees were thinned by hand to commercialbearing levels five weeks later and the numbers of fruit removed wererecorded. The compound significantly reduced the required hand thinningas shown in the table below. All trees were harvested and the fruitcounted and weighed at the end of the growing season. The treesreceiving the treatments with the subject compound produced fruit ofequivalent weight and numbers as controls:

Number of Average fruit yield per tree peaches removed Percent TotalPercent Application by hand Total of weight of rate (p.p.m.) thinningcount control (lbs.) controls Similar studies have shown a positivethinning response to 1,1,5,5 teramethyl 3 dimethylaminodithiobiuret bythese additional peach varieties: Loring, Ranger, Triogem, Alberta,Ambergem, Early Red, Rio-Oso-Gem, Redskin, Baby Gold, Baker SOLG,'Sunhigh, Daly, Early Amber, Brays Late White, Autumn, Comancha.

EXAMPLE Treatment: Observed eflect Control lanolin only None, none.1,1,5,5, -tetramethyl-3-di1neth- Abscissed, abscissed.

ylamino-dithiobiuret.

1,1,5,5 tetramethyl 3 (N- Do.

methyl anilino) dithiobiuret. 1,1 dimethyl-3-dimethylami- Do.

no S-ethyl-S-phenyl dithiobiuret.

In summary, the unique properties of these compounds are useful asabscission-control agents to adjust the rate and timing of abscission offlowers, fruits (including citrus-stone, pome fruits), nuts, berries,floral and vegetable crops; as mature crop harvest aids applied to laterstages of the maturing crop to control the rate of final development andmaturation of the crop and regulate the timed abscission of the maturefruit, vegetables, nuts or berries; as foliar maturation control agentsapplied to forage, turg, horticultural and ornamental plants or crops todelay the onset of normal maturation processes such as senescence ordefoliation thereby providing continued vegetative growth and/or moreintensely colored foliage so as to provide higher yields of forage cropsand more desirable foliage on other plants and turfs; as crop-pruningagents applied to cucurbits and other vine crops and indeterminatevegetables several days or weeks prior to harvesting to stimulateabscission of young fruit and flowers, leaving only the earlier settingor maturing fruit for subsequent harvest during a concentrated timeperiod; as plant sex expression modifiers applied to cucurbits toincrease the ratio of female to male flowers thereby increasingsubsequent crop yields; as a preventative of sucker shoots from growingon tobacco plants thereby stepping up the prime leaf yield so as toreduce the growers cost; as a preventative of wrinkling and shrinking orsoftening of fresh vegetables when stored or shipped; as a preventativeof the sprouting of onions and potatoes when in storage.

The plant growth regulants mentioned hereinabove, although safe tohandle, and operative under very favorable conditions over a longerperiod of application time, nevertheless must be employed within arelatively narrow limit of concentration or else overthinning, epinastyand other serious damage to foliage and shoots will occur.

What is claimed is:

1. A method for controlling the abscission of buds, flowers and fruitsof plants by treating said plants with a composition consistingessentially of an elfective amount of1,1,5,5-tetramethyl-3-dimethylaminodithiobiuret in admixture with aninert diluent.

2. A method according to claim 1 wherein 1,1,5,5-tetramethyl-3dimethylaminodithiobiuret is applied to said plants at an appropriatetime and in a suflicient concentration prior to the harvest date therebycontrolling the abscission of mature fruit of said plant.

3. A method for controlling the onset and rate of development ofmaturation and onset of senescense thereby increasing the continuedvegetative growth and intensely colored foliage of said plants byapplying to said plants the composition of claim 1.

4. A method according to claim 1 wherein said compound is applied in anamount ranging from .1 to 3 lbs./

acre.

References Cited UNITED STATES PATENTS 3,556,766 1/1971 Mitchell 711203,189,431 6/1965 Salzberg 71-120 3,318,680 5/1967 Levitt 7199 JAMES O.THOMAS, J 11., Primary Examiner US. Cl. X.R.

